Because of the extraordinarily large size of its nervous system cells (some of which are almost a millimeter in diameter) and the ability to recognize these cells as unique individuals, the mollusc Aplysia has proven extremely useful for studying properties of individual cells, the patterns of interconnections, modulation of synaptic strength, behavior, circadian rhythms, learning and development. The purpose of the meeting is to bring together, for the third time, the Aplysia neurobiology community throughout the world and continue the highly successful biannual series of Aplysia meetings that were initiated in 1988. The third meeting will again provide a format for discussing new methods and findings that have emerged in the cell and molecular biology of Aplysia. These findings will be considered in eight different sessions, each concerned with a different level of analysis: 1. Molecular biology of ion channels and channel modulation by second messengers 2. Peptides and small molecule transmitters 3. Molecular mechanisms of synaptic transmission 4. Cell imaging 5. Circadian rhythm 6. Neuronal circuitry and behavior 7. Learning 8. Development